Aqueous inkjet ink composition

Abstract

An aqueous inkjet ink composition suitable for printing on a hydrophobic surface such as a vinyl surface including an aqueous vehicle, a self-dispersed pigment, a silicone-containing surfactant and an aqueous emulsion polymer having a glass transition temperature (Tg) of from −40° C. to 150° C. Also provided is a method for printing an image on a hydrophobic substrate.

1. An aqueous inkjet ink composition for printing on a hydrophobic surface comprising:
 a) an aqueous vehicle; 
 b) a self-dispersed pigment; 
 c) a silicone-containing surfactant; 
 d) benzyl alcohol and nonylphenol polyethylene glycol ether; and 
 e) a polymer having a glass transition temperature (Tg) of from −40° C. to 150° C. 
 wherein the polymer has a swollen outer shell, and wherein the swollen outer shell has a thickness of greater than or equal to 50 nm as determined by the difference of the weight average particle size measurement using capillary hydro-dynamic fractionation (CHDF) and the volume average particle size measurement using dynamic light scattering (DLS). 
 
     
     
       2. The composition of  claim 1  wherein the aqueous emulsion polymer has a Tg of from 40° C. to 100° C. 
     
     
       3. The composition of  claim 1  wherein the self-dispersed pigment is selected from the group consisting of anthroquinones, phthalocyanine blues, phthalocyanine greens, diazos, monoazos, heterocyclic yellows, pyranthrones, quinacridone pigments, dioxazine pigments, indigo, thioindigo pigmepts, perynone pigments, perylene pigments, isoindolene, polymer particles having at least one void, oxidized carbon black, carbon blacks that do not require an additional atomic group to bind the carbon black with a hydrophilic group, titanium dioxide, iron oxide, metal powders, and combinations thereof. 
     
     
       4. An ink set comprising a plurality of inks according to  claim 3 . 
     
     
       5. A method for printing an image on a hydrophobic substrate comprising the steps of:
 a) jetting onto a hydrophobic surface an aqueous inkjet ink composition comprising:
 i. an aqueous vehicle; 
 ii. a self-dispersed pigment; 
 iii. a silicone-containing surfactant; 
 iv. benzyl alcohol and nonylphenol polyethylene glycol ether; and 
 v. a polymer having a glass transition temperature (Tg) of from −40° C. to 150° C.; and 
 
 b) drying the aqueous inkjet ink composition; 
 wherein the polymer has a swollen outer shell, and wherein the swollen outer shell has a thickness of greater than or equal to 50 nm as determined by the difference of the weight average particle size measurement using capillary hydro-dynamic fractionation (CHDF) and the volume average particle size measurement using dynamic light scattering (DLS). 
 
     
     
       6. The method of  claim 5  wherein the aqueous emulsion polymer has a Tg of from 40° C. to 100° C. 
     
     
       7. The method of  claim 5  wherein the self-dispersed pigment is selected from the group consisting of anthroquinones, phthalocyanine blues, phthalocyanine greens, diazos, monoazos, heterocyclic yellows, pyranthrones, quinacridone pigments, dioxazine pigments, indigo, thioindigo pigments, perynone pigments, perylene pigments, isoindolene, polymer particles having at least one void, carbon black, titanium dioxide, iron oxide, metal powders, and combinations thereof. 
     
     
       8. The method of  claim 5  wherein the hydrophobic surface comprises polyvinyl chloride, polyester or polypropylene. 
     
     
       9. The method of  claim 5  further comprising the step of heating the surface and/or the image rendered upon it before the drying step.